by Douglas Robson, USA TODAY Sports

by Douglas Robson, USA TODAY Sports

Facing a two-set deficit against an unseeded player making his Wimbledon quarterfinal debut, Andy Murray exorcised the tournament's upset demons with a stirring five-set comeback victory against veteran Fernando Verdasco of Spain on Wednesday.

"I came through an incredibly tough match," No. 2 Murray told BBC as he left the court following his 4-6, 3-6, 6-1 6-4, 7-5 Centre Court win against No. 54 Verdasco. "It could have gone either way."

Murray, the reigning U.S. Open champion and last year's Wimbledon runner-up, reached his fifth consecutive All-England Club semifinal

"Made some bad mistakes, poor choices on the court," Murray said. "And then, I turned it around really well after that."

The 26-year-old Scot faces No. 24 seed Jerzy Janowicz, who became the first Polish man to reach a Grand Slam semifinal by smashing 30 aces on his way to beating countryman Lukasz Kubot 7-5, 6-4, 6-4.

The other men's semifinal pits No. 1 Novak Djokovic and No. 8 Juan Martin del Potro - the only two players yet to drop a set.

Del Potro, the 2009 U.S. Open winner, survived a scare on his already heavily taped knee in the first game against No. 4 David Ferrer of Spain. The 6-foot-6 Argentine crumpled to the ground but continued on, blasting French Open finalist Ferrer out of the tournament 6-2, 6-4, 7-6 (7-5).

Djokovic, the top seed from Serbia, dug out of a two-break deficit in the second set to ease past powerful No. 7 seed Tomas Berdych of the Czech Republic 7-6 (7-5), 6-4 6-3.

"Coming into the semifinals I feel physically fresh," said Djokovic, who is seeking his second Wimbledon title and seventh major overall. "And I'm ready. Plenty of motivation to win every match that I play here."

Djokovic reached his 13th consecutive Grand Slam semifinal since losing in the quarterfinals of the 2010 French Open.

With the Centre Court crowd roaring encouragement and desperate for a British male champion after 77 years, Murray found his back to the wall against Verdasco.

"I just started making mental errors, made some bad mistakes," said Murray after he squandered a 3-1 lead in the second set.

But he changed tactics, slowed the pace down, started to put more returns in play.

Despite his ranking, Verdasco is no Johnny-come-lately.

Once ranked as high as No. 7, the 29-year-old lefthander beat Murray in the fourth round of the 2009 Australian Open.

He arrived at Wimbledon with a 9-12 record but showed the firepower and risk-taking, especially on his second serve, that have made him a dangerous opponent for years.

"When he was break points down on second serves he wasn't slowing it down or going for the middle of the box," Murray said. "He was going for the lines and came up with some huge serves on big moments throughout the whole match really."

Del Potro looked to be out of the tournament in the first game of his match, when he hyperextended his left knee and fell to the ground on the fifth point.

"To be honest, I didn't want to retire (being) in the quarters for first time at Wimbledon," del Potro said. "And that's the reason for continuing play. The doctors gave me good anti-inflammatories."

After a break of about 10 minutes, del Potro was back on the court. He broke Ferrer twice in the first set, then moved easily through the second and third against one of the grittiest players in tennis.

"I have my knee problem, but always the opponent, the other players, can have different injuries, too," del Potro said. "You have to be strong, more than the rest."

When the matchup of Polish quarterfinalists ended, the compatriots embraced at the net for 20 seconds, and following that exchanged shirts. Janowicz then sat in his chair, clasped his hands over his nose and cried.

"Right now, I'm the most happy person in the world," Janowicz said.

Kubot waited for his countryman, and they walked together off the court, hand in hand for part of the time.

About playing Murray, Janowicz said: "I hope Andy will feel some kind of pressure. I'm sure he'll feel some kind of pressure because Great Britain is waiting for the English champion in Wimbledon."

This year's Wimbledon has been full of surprises, upsets and unexpected turns of events. Rafael Nadal went out in the first round; Roger Federer, Maria Sharapov and Victoria Azarenka in the second. Overwhelming favorite on the women's side Serena Williams lost in the fourth round. The slippery grass has caused multitudes of falls and complaints. None of the four women's semifinalists are major champs.

Though del Potro is clearly struggling with a painful knee injury, his game has been in spectacular form. Not just the feared forehand, but the serve, reminding observers of the player who swept past Roger Federer to win the 2009 U.S. Open.

Del Potro is 3-8 lifetime against Djokovic, though one of those victories came here, at the All England Club, when he beat the Serb in the Olympic bronze-medal match last year. Del Potro also won their last meeting, earlier this year on hardcourt at Indian Wells.

"He struggled with injuries in last few years, but every time he comes back, he comes back very strong because he just has this talent," Djokovic said.

Del Potro's victim Wednesday, Ferrer, also was a member of the injured brigade. He twisted an ankle in his opening match and has been dealing with it ever since.He cut short his pre-match hitting session because of pain in his ankle but said that was no excuse. Ferrer, who crossed the net to run toward del Potro to check on him when he fell, said he didn't see much change in his opponent's play after the injury.

"Juan Martin, he was more focused, he was playing more aggressive than me and he served very, very good in all three sets," Ferrer said.